The Indiana University Multipurpose Arthritis Center (IUMPAC) consists of a Biomedical Research Component, an Education/Epidemiology/Health Services Research (EEHSR) Component and an Administration Unit. Major biomedical research interests include articular cartilage biology, pathogenesis of articular cartilage breakdown in osteoarthritis (OA), causes of pain and disability in OA, amyloidosis, immunologic tolerance, and pathogenesis of dermatomyositis. Six new Developmental/Feasibility studies are proposed in this application: they include projects related to gelatinase (type XI collagenase) activity in OA cartilage; the development of methodology for documenting the presence of muscular reflexes that protect joints; the effects of eicosanoids on release of neurotransmitters from peripheral and spinal cord neurons; the efficacy of ultrasound technology for reliable reproducible measurement of articular cartilage thickness and roughening; the effects of lymphocyte proteases on endothelial cell permeability; and anti-phospholipid antibodies. Our EEHSR Component is concerned with training of Fellows, house staff, medical students and arthritis health professionals (AHPs) and includes outreach programs and a variety of interactions with community organizations. Three new EEHSR projects are proposed: one examines lower extremity weakness as a risk factor for pain and disability in OA. The second examines muscle strength as an outcome variable in patients with hip fracture admitted to nursing homes, and the third examines clinical and economic effects of patient education in OA. To support the research activities of IUMPAC 4 Core Units are proposed: Protein Chemistry, Molecular Biology, Biostatistics and Data Acquisition. Overall Center activities are supported by an Administration Unit.